Version: 25.11.27. You'll need to add "udf" prior your search. For example "udf-lead-user-id:23" would search for the user id 23 in the UDF field "lead_user_id". For dates or integer/number fields, we support the usual ranges, for example "udf-profit:100-1000". Booleans are now also supported for example, "udf-needs-archiving:true". Please contact us if you don't know the name of your user defined fields.